With the development of modern science and technology, the effects of electromagnetic radiation on the environment are becoming increasingly serious. At the airport, aircrafts could not take off due to electromagnetic interference and are delayed. In the hospital, a plurality of electronic diagnosis and treatment apparatuses cannot work properly due to interferences of mobile phones. Therefore, controlling electromagnetic pollution and searching for a kind of wave-absorbing material for resisting and weakening electromagnetic radiation have become a major issue in material science.
Wave-absorbing material can effectively absorb incident electromagnetic waves and make incident electromagnetic waves be scattered and attenuated. Wave-absorbing material can convert the incident electromagnetic wave into heat or other forms of energy through various loss mechanisms of the material for the purpose of absorbing wave. Wave-absorbing material includes structural wave-absorbing material and coated wave-absorbing material. The former mainly is wedge-shaped, bubble-shaped, flat-shaped and etc. The latter is compounded by binder and absorbent, the absorbing ability is mostly related to the type of the absorbent. However, each type of the wave-absorbing material has a constant absorbing frequency band which cannot be changed freely.
A new synthetic material, called artificial electromagnetic material (metamaterial), has a feature that it can be designed freely according to different working frequency band, and therefore comes to be a new direction in the study of wave-absorbing material.
The artificial electromagnetic material is new synthetic material which can respond to electromagnetic waves. Referring to FIG. 1, the artificial electromagnetic material includes a substrate and a plurality of artificial microstructures attached to the substrate. Since the artificial microstructures usually have a certain shape such as “I” shape constructed by metal wires, the microstructures can respond to electromagnetic waves, thereby the artificial electromagnetic material reflects different electromagnetic properties from that of the substrate. Designing artificial microstructures with special properties, a broadband wave-absorbing material can be achieved. And if sizes and shape of the artificial microstructures are changed, the absorbing band of the artificial electromagnetic material will be changed.